Richt angle

In geometry an trigonometry, a richt angle is an angle that bisects the angle formed bi twa halves o a straicht line. Mair precisely, if a ray is placed so that its endpynt is on a line an the adjacent angles are equal, then thay are richt angles.[1] As a rotation, a richt angle corresponds tae a quarter turn (that is, a quarter o a full circle).[2]